Adam Clarke's Commentary on the Bible

Verse 43 (Joshua 21:43)

And the Lord gave - all the land which he sware - All was now divided by lot unto them, and their enemies were so completely discomfited that there was not a single army of the Canaanites remaining to make head against them; and those which were left in the land served under tribute, and the tribute that they paid was the amplest proof of their complete subjugation. Add to this, they had as much of the land in actual possession as they could occupy; and, as they increased, God enabled them to drive out the rest of the ancient inhabitants; but in consequence of the infidelity of the Israelites, God permitted their enemies often to straiten them, and sometimes to prevail against them. It should also be remembered, that God never promised to give them the land, or to maintain them in it, but on condition of obedience; and so punctually did he fulfill this intention, that there is not a single instance on record in which they were either straitened or subjugated, while obedient and faithful to their God.

The cavil is as foolish as it is unprincipled which states, "The Israelites never did possess the whole of the land which was promised to them, and therefore that promise could not come by Divine revelation." With as much reason might it be urged that Great Britain has not subdued the French West India Islands and Batavia, (Feb. 1812), because the ancient inhabitants still remain in them; but is not their serving under tribute an absolute proof that they are conquered, and under the British dominion? So was the whole land of Canaan conquered, and its inhabitants subdued, though the whole of the ground was not occupied by the Israelites till the days of David and Solomon. In the most correct and literal sense it might be said, There failed not aught of any good thing which the Lord had spoken unto the house of Israel: all came to pass. Nor shall one word of his ever fail to any of his followers while the sun and moon endure.

- Adam Clarke's Commentary on the Bible